Digital image capture devices are well known in the art and may be used to capture digital images of objects. One of the more common digital image capture device is the digital camera, which allows its user to take digital photographs that may ultimately be transferred or downloaded to a computer for viewing and/or editing.
Scanner devices are also a common type of digital image capture device. Although scanner devices may be used in various ways, scanner devices are often used to convert traditional photographs into digital format. For example, a color optical scanner device, such as a flatbed scanner, may be used to produce machine-readable color image data signals that are representative of a traditional photograph. In a typical scanner application, the color image data signals produced by the scanner may be used by a computer to reproduce a digital image of the scanned object on a suitable display device, such as a cathode ray tube (“CRT”) or liquid crystal display (“LCD”). Alternatively, the computer may print the image of the scanned object on a printer. Indeed, by using a scanner and a high quality color printer, the need for traditional film processing may be eliminated entirely.
Scanners, digital cameras, and the computers to which they may be linked continue to decrease in price while increasing in quality. Moreover, with the continually developing technologies, the process of capturing, viewing and editing digital images is even becoming easier. As a result, more people find themselves using computers, scanners, and/or digital cameras to capture, view, edit and share (e.g., email over the Internet) digital images.
Although digital image capture devices are relatively easy to use, many digital images produced by such devices nevertheless contain areas or regions of noise that can diminish the visual quality of the digital image. For example, the digital image may contain a pixel having a color that is not consistent with the color of adjacent or surrounding pixels. Such irregularly colored pixels may commonly be referred to as noise speckles, impulsive noise, and/or salt-and-pepper noise. The digital image may also contain larger noise areas or regions (e.g., larger than one pixel). That is, the digital image may contain a group of adjacent pixels having a color or colors that are inconsistent with the color(s) of adjacent or surrounding pixels. Such irregularly colored groups of adjacent pixels may be commonly referred to as noise splotches or blotches.
The cause or source of noise speckles and/or noise splotches in a digital image may vary. For example, noise speckles and splotches may be especially problematic when relatively old traditional photographs are converted to digital format with such noise being caused by the photograph's condition and/or the equipment being used to convert the photograph to digital format. By way of example, the original photograph may have stains, faded areas, wrinkles, etc. which appear as noise in the resulting digital image. Or for example, dust may have been present on the scanning bed when the photograph was scanned. In any event, noise arising from the same source (e.g., dust on the scanning bed, wrinkles in the source object, etc.) should have the same image data (e.g., color profile) associated with it.
Typically, digital images, after being captured, are downloaded to a computer system so that they may be edited with readily available software applications such as Adobe Photoshop®, available from Adobe Systems Incorporated, San Jose, Calif. Such software applications provide a wide range of editing features such as “red-eye” reduction and poor lighting correction. Some software applications also allow for the filtering of noise speckles. However, such software applications do not usually provide an automated filtering process for the larger areas of noise splotches due to the difficulties associated with distinguishing noise splotches from details in the digital image being filtered.